Ignition system for internal combustion engines



Dec. 31, 1963 F. M. FOSTER 3,116,379

IGNITION SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed Aug. 18, 1960lllli! IN V EN TOR. fiv/vk M 5 .s'rzae United States Patent 3,116,379IGNITHQN SYSTEM FOR INTERNAL CQMBUSTEQN ENGINES Frank M. Foster, SouthPasadena, Calili, assignor to Seas, Ltd, South Pasadena, Calilh, acorporation of (Ialifornia Filed Aug. 18, 1960, Ser. No. 50,358 9Claims. (til. 200-) The invention relates to a spark ignition system forinternal combustion engines, particularly to a circuit 7 breaker in theignition system to produce successive high voltage pulses of current forignition with the engine spark plugs.

The invention provides a circuit breaker of the type des ribed abovewhich is reliable and durable, which permits more precise timing of theigniting spmk at the spark plugs in relation to rotation of the enginecrankshaft, and which operates with minimal pitting and carbonization ofits electrical contact points.

Conventional spark ignition systems for internal cornbustion enginesinclude a step-up transformer or coil which has a low voltage primarywinding of few turns connected in a series primary circuit with a lowvoltage source of potential and with a circuit breaker. The transformerhas a secondary winding, of many more turns than the primary winding,which is connected successively in a series secondary circuit with thespark gap of each spark plug, at the proper time for ignition of theair-fuel mixture in the cylinder, by a distributor rotor, rotativclydriven in timed synchronism with the rotation of the engine crankshaft,and by an adjacent circular arrangement of terminals, each connected inseries to one of the spark plug gaps.

The primary circuit is normally closed to permit current fiow throughthe primary winding of the transformer to build up a magnetic flux fieldabout the secondary windings. The primary circuit is periodically openedfor a short time interval by the circuit breaker in the primary circuitin timed synchronism with the distributor rotor and the rotation of theengine crankshaft. The opening of the primary circuit causes themagnetic flux field to collapse and thereby induce a high voltagecurrent in the secondary winding of the transformer, which causes aspark to jump the spark gap of the spark plug.

The circuit breaker is conventionally operated by a cam fixed to thedistributor rotor shaft for rotation with the shaft in timedsynchronisrn with the engine crankshaft and with the distributor rotor.The distributor rotor normally closes the secondary circuit to theproper spark plug for an appreciable length of time, and the opening ofthe primary circuit, and thus the igniting spark at the spark gap ofsuch proper spark plug, is selectively timed to occur at the propermoment during the power stroke of the engine by adjusting the rotaryposition of the circuit breaker about the distributor rotor shaft.

The working surface of the conventional circuit breaker cam is ofrelatively small diameter. This results in a relatively small arc ofdisplacement of its working surface 'for a given rotary angulardisplacement of the engine crankshaft and the distributor shaft. As aresult, actuation of the circuit breaker is undersensitive in relationto the rotational cycle of the engine crankshaft, and this is adisadvantage because it makes difficult the selective adiustment of thecircuit breaker and cam to open the primary circuit at precisely thecorrect moment during such rotational cycle of the engine crankshaft.

Another disadvantage of conventional circuit breakers is the fact thatthe circuit breaker points tend to spark when they are separated to openthe primary circuit, and

this causes pitting and carbon deposition on such points, leading tounreliability and ultimate failure thereof.

The invention removes the above disadvantages by means of a circuitbreaker wherein the contact points rotate and are actuated to open andclose the primary circuit by means of structure spaced concentricallyfrom the center of rotation of the contact points.

The rotation of the points results in an air stream past the points.This air stream tends to prevent sparking between the points when theyare separated, and thus reduces pitting and carbon deposition on thepoints.

The spacing of the actuating structure from the center of rotation ofthe points results in a larger arc of displacement about such center fora given rotary angular displacement of the engine crankshaft. As aconsequence, the sensitivity of the actuation of the circuit breaker inrelation to the rotation of the engine crankshaft is increased. Thismakes it possible, through selective adjustment of the circuit breaker,to time more precisely the opening of the primary circuit in relation tothe rotation of the engine crankshaft.

The structure of the invention includes a member surrounding andextending transversely of a rotary shaft rotatable synchronously withthe crankshaft of the engine, such as a conventional distributor shaft.The member has a plurality of cam portions for actuation of a followerin a direction axially of the shaft arranged symmetrically andconcentrically about the shaft in equal spaced relation therefrom and inspaced relation to each other. A first arm is fixed to the shaft forrotation therewith and extends radially therefrom. A second resilientflexible arm is fixed to the shaft for rotation therewith and extendsradially therefrom for displacement axially of the shaft by the camportions. Electrical contact points are provided on the first and secondan. s which are adapted to alternately engage and disengage responsiveto displacement of the second arm in opposite directions by the camportions. The electrical contact points are spaced from each other andconnected in series with the primary winding of a conventionalelectrical induction transformer and source of potential in the ignitioncircuit to effect alternate opening and closing of such circuit, whichthereby induces successive pulses of high voltage current in thesecondary winding of the transformer.

The invention and its advantages will be fully understood from. areading of the following description, taken in conjunction with theaccompanying drawings, in which:

'PlG. l is a schematic circuit diagram of the ignition system for aninternal combustion engine and a plan view of the distributor in suchsystem embodying the invention;

FIG. 2 is a vertical section along the line 22 in PEG. l; and

3 is a vertical section along the line 3-3 in FIG. 1.

Referring to 1, ill is the case of a conventional automobile distributorwith the ca and rotor removed. A conventional rotatable distributorshaft ll extends through the distributor to be rotatively driven inconventional manner synchronously with the crankshaft of the engine asrepresented by meshed gears '7 and S and by shaft rotatably drivingshaft ll by connection through the gears. The conventional advance platein such distributors is shown schematically at 12. The advance plate isnormally stationary relative to the distributor shaft, except for smallamounts of rotation thereof responsive to conventional mechanism toadvance and retard the tim ing of the engine. Although the invention isdescribed herein in conjunction with a conventional automobile ignitiondistributor and distributor she. t, it is to be understood that theinvention may comprise a unit separate 3 from the distributor with aseparate rotatable shaft rotatively driven in conventional mannersynchronously with the engine crankshaft performing the functions of thedistributor shaft.

A cam plate 15, preferably annular in shape, is disposed on the advanceplate i2. and extends transversely of the axis of the distributor shaft11. If the cam plate is the preferred annular shape, it is disposedcoaxially with the distributor shaft. The cam plate is releasably fixedto the advance plate in non-rotatable position with conventional means,such as a plurality of tabs receiving screws threadedly received in theadvance plate, as shown for the tab 16 and screw 17. Although the camplate is fixed to the advance plate in non-rotatable position, it isadapted to be so fixed in preselected rotary ositions about the axis ofthe distributor shaft 11, this being permitted in conventional manner,as by arcuately slotted holes, such as the hole 18, in the tabs. Thus,the cam plate may be released from the advance plate, positioned in aselected rotary position about the axis of the distributor shaft, andnon-rotatably releasably fixed in such position.

Disposed about the outer periphery of the cam plate in spaced relationto the distributor shaft are a plurality of cam portions, such as thecam portions 20 and 21. Each cam portion extends in a directiontransverse to the plane of the cam plate and parallel to the axis of theshaft 11 a greater amount than the extent in the same direction of theportion of the cam plate between it and the next cam portion, as bestshown in FIG. 3 for the cam portions 29 and 21 and the portion of thecam plate therebetween 22. All the cam portions are identical and aresymmetrically, equally and concentrically spaced about the axis of thedistributor shaft. The cam portions are each arcuate in the plane of thecam plate with a constant and common radius about the distributor shaftso that they are concentric therewith. Each cam portion is of equal arclength about the axis of the distributor shaft. The profile of the camportions in a curved plane transverse to the plane of the cam plate andconcentric with the axis of the distributor shaft may vary forparticular applications, but in general will be as shown in FIG. 3,wherein the cam portion 20 has an approach ramp 23 extending angularlytransversely of the plane of the cam plate, a dwell portion 24 whichextends substantially parallel to the plane of the cam plate and anabrupt retreat 25 which extends to the portion 22 of the cam platebetween the cam portion 2% and the ramp of the next succeeding camportion 21. It is thus apparent that the cam portions are designed sothat a follower rotating about the axis of the distributor shaft in thedirection indicated with the arrow 13 in FIG. 1 is displaced alternatelyin opposite directions transverse to the plane of the cam plate andaxially of the distributor shaft, the displacement being up responsiveto the cam portions and down responsive to the portions between camportions.

A rotor 3t? is disposed on the distributor shaft ill and is fixedthereto for rotation with the distributor shaft with conventional means,as a setscrew 31 threadedly received through the rotor and engaging thedistributor shaft.

An actuating arm 32 extends radially from the rotor 3th in juxtaposedrelation to the cam plate 15 and to the cam portions thereof and isfixed to the rotor for rotation therewith, as by means of a ring portion33 connected to the rotor in conventional manner. The arm 32 is made ofresilient, spring material, such as spring steel. Mounted on the arm 32is a follower member 34- which may be a cylindrical contact point asshown, a roller, or a skid portion of the arm 32 itself. The followermember 34 is aligned with the cam portions on the cam plate with its endnormally disposed below the dwell surfaces of the cam portions, such asthe dwell 24 of the cam portion Zil, so that when it is in contact ,4with such dwell surfaces, as shown in FIG. 2, the actuating arm isdisplaced upwardly and when it is disposed between the cam portions thearm is displaced downwardly through resilient flexure thereof. Thus itis apparent that as the distributor shaft 11 rotates, the actuating armrotates therewith and its follower member successively engages anddisengages the cam portions to cause the actuating arm to displacesuccessively in opposite directions axially of the shaft.

Also fixed to the rotor for rotation therewith is an butment arm 35,which may be so fixed by means of a ring portion 36 connected to therotor 30 in conventional manner. The arm 35 extends radially from thedistributor shaft in juxtaposed spaced relation to the actuating arm. Itis made of springy, resilient material, such as spring steel, the sameas the actuating arm 32, although it is apparent that the abutment armneed not be springy and resilient and may be made of other material.

An electrical contact point 37 is fixed to the actuating arm 32 andanother electrical contact point 38 is fixed to the abutment arm 35. Thecontact points 37, 38 are aligned and made of electrically conductivematerial such as is commonly found in the contact points forconventional distributor circuit breakers. The contact points 37 and 38are spaced from each other axially of the shaft 11 a maximum amountwhich is less than the maximum displacement of the point 37 resultingfrom displacement of the arm 32 responsive to engagement of the followermember with the cam portions, so that the points 37 and 33 alternatelyengage and disengage to close and open an electrical circuit completedtherethrough, as will be described below, responsive to the alternatedisplacements of the arm 32 in opposite directions as described above.As illustrated in FIG. 2, the contact points 37 and 38 are spaced fromone another so that they do not engage when the follower member 34 isbetween cam portions and do engage when the follower member is incontact with a cam portion. As shown in FIG. 2, when the follower member34 engages a cam portion, both the arm 32 and the arm 35 are resilientlydisplaced upwardly which, due to the spacing of the contact pointsdescribed above, results in positive urging together of the contactpoints 37 and 38 to close a circuit therethrough effectively andreliably. It is apparent that other arrangements may be adopted withinthe scope of the invention for the alternate engagement anddisengagement of the contact points 37 and 33, such as, for example,disposing the arm 35 intermediate the arm 32 and the cam plate anddesigning the cam portions so that the contact points will be disengagedwhen the arm 32 is displaced upwardly responsive to a cam portion andengaged while the follower member of the arm is disposed intermediatethe cam portions. Also, if desired, a plurality of pairs of actuatingand abutment arms may be used, each pair of such arms having a set ofcontact points and operating as described above, so that a plurality ofcontact points synchronously engage and disengage for more reliableclosing and opening of the circuit.

The contact surface of one of the contact points is arcuate, as at 39,so that the radial displacement of one contact point relative to theother as the first and second arms flex upwardly results in a wipingaction between the points in a plane substantially parallel to the planeof the cam plate 15 which tends to prevent formation of carbon depositsand the like on the contact surfaces of the points.

The contact points 37, .33 are electrically insulated from each otherwhen they are disengaged and are disposed in an electrical circuit asdescribed below. For this reason the rotor 3th is made of dielectricmaterial and the arms 32, and 35 are made of electrically conductivematerial to which the contact points are fixed in electricallyconductive relation. Electrical circuitry is completed to the arm 32through the ring 3-3 thereof, the setscrew 31 con.-

ductively engaging the ring 33 and the distributor shaft iii, anelectrically conductive leaf spring 4d fixed to the advance plate illwith mount 42 and screw 41 and hearing against the distributor shaft litin resiliently displaced condition, and a conventional electricalconnection 14 of the advance plate to a ground terminal 43. Electricalcircuitry is completed to the contact point 38 by means of a second leafspring which at one end is fixed to a stationary terminal and isresiliently displaced with its free end portion engaging on the ring 36of the arm 3:? to effect a reliable electrical connection between thespring dd and the ring 36. Thus, electrical connections to the arms 3-2and 35 are maintained during rotation of such arms with the rotorthrough the sliding engagement of the leaf springs and dd with therotating shaft ll and ring 36, respectively.

Referring now to MG. 1, circuitry and apparatus for a spark ignitionsystem for an internal combustion engine are schematically shown. Aconventional electrical induction transformer, or spark coil, isindicated at and has a primary winding 551 of few turns and a secondarywinding 52. of many turns. The primary winding fill is connected in aseries primary circuit to a conventional source of low voltage potential56, a conventional condenser 57, and also the contact points 37, Theconnection of the contact points 3'7 and 38 in the primary circuit isaccomplished through the terminals 43 and 45 and the electricalconnection of the contact points thereto as described above. The contactpoints 37 and are in engagement during the time the fol-lower member 34engages a cam portion, which thereby closes the primary circuit andpermits a magnetic iiux field to be built up about the secondarywindings 52 by the primary windings :31 as a result of current flowingtherethrough from the source of potential When the follower member Edreaches the retreat of a cam portion, such as the retreat of the camportion 2, it displaces away from the arm and causes the contact points3'7 and to disengage and thus open the primary circuit. The opening ofthe primary circuit causes the magnetic field to decay or fall, therebyinducing a high voltage current in the secondary coil winding 5'2. Thishigh voltage electrical current is conducted to the proper spark plug intimed relation to the operation of the engine by means of a conventionaldistributor rotor mounted on the distributor shaft for rotationtherewith which ro tates and completes successively a circuit to each ofthe spark plugs through a terminal for each spark plug, such as acircuit to the spark plug gap 55 through the terminal to cause a sparkacross the spark plug it is an parent that the cam plate is selectivelypositioned about the distributor shaft ll in such rotary position thatthe portions of the cam plate between the cam portions are properlyoriented with respect to the distributor shaft ill and rotor and withrespect to the rotational cycle of the engine crankshaft so that thehigh voltage current produced by the opening of the primary circuit as aresult of disengagement of the contact points 25", and 33 occurs at theproper time during the rotational cycle of the engine crankshaft andcorresponds with the comple* tion of an electrical circuit through thesecondary winding to the proper spark plug. This timing is accomplishedin conventional manner as a result of the rotary adjustability of thecam plate relative to the rotor shaft ill; per mitted by the means forreleasably attaching the cam plate to the advance plate, as describedabove. The [lllu ing is greatly facilitated and may be accomplished withmore precision than conventionally because the cam portions are spacedfrom the distributor shaft and hence extend a greater are distance aboutthe distributor shaft for a given rotary angular displacement of suchshaft than the conventional circuit breaker cam, which increases thesensitivity of the actuation of the contact points relative to therotation of the engine crankshaft f5 and the rotation of the distributorshaft, as explained in the introductory portion hereof.

I claim:

1. A circuit breaker comprising a rotary shaft, means for rotating theshaft, a member surrounding the shaft and extending transversely of theaxis of the shaft, a plurality of cant portion means on the memberequally spaced from the shaft concentrically with its axis and spacedfrom each other about the shaft for displacement of a cam followeraxially of the shaft, a first arm fixed to the shaft for rotationtherewith and extending radially therefrom, a second resilient flexiblearm fixed to the shaft for rotation therewith and extending radiallytherefrom, said first and second arms being juxtaposed and spaced fromeach other axially of the shaft, cam followor means disposed on thesecond arm engageable with the cam portion means for displacing thesecond arm in opposite directions axially of the shaft responsive toengagement and disengagement of the cam follower means with the camportion means, a first electrical contact on the first arm, a secondelectrical contact on the second arm in spaced aligned relation axiallyof the shaft to said first electrical contact, and means connected tothe first and second contacts for conducting electrical current throughthe contacts when the contacts are engaged and the second electricalcontact, whereby an electrical circuit is alternately closed and openedthrough engagement and disengagement of the first and second electricalcontacts responsive to displacement of the second arm by the cam portionmeans.

2. A circuit breaker, comprising a rotary shaft, means for rotating theshaft, a member surrounding the shaft and extending transversely of theaxis of the shaft, a plurality of cam portion means on the memberequally spaced from the shaft concentrically with its axis and spacedfrom each other about the shaft for displacement of a cam followeraxially of the shaft, a first resilient flexible arm fixed to the shaftfor rotation therewith and extending radially therefrom, a secondresilient flexible arm fixed to the shaft for rotation therewithextending radially therefrom, said first and second arms beingjuxtaposed and spaced from each other axially of the shaft, cam followermeans disposed on the second arm engageable with the cam portion meansfor displacing the second arm in opposite directions axially of theshaft responsive to engagement and disengagement of the cam followermeans with the cam portion means, a first electrical contact on thefirst arm, a second electrical contact on the second arm in alignedrelation to said first electrical contact, said first and secondelectrical contacts being spaced from each other axially of the shaft amaximum amount which is less than the displacement of the secondelectrical contact resulting from said displacement of the second arm,and means connected to the first and second contacts for conductingelectrical current through the contacts when the contacts are engaged,whereby an electrical circuit is alternately closed and opened throughengagement and disengagement of the first and second electrical contactsresponsive to displacement of the second arm by the cam portion means.

3. A circuit breaker comprising a rotary shaft, means for rotating theshaft, a non-rotatable member surrounding the shaft and extendingtransversely of the axis of the shaft, a plurality of cam portions onthe member extending therefrom longitudinally of too axis of the shaftand radially spaced equally from the axis of the shaft concentricallywith such axis, said cam portions being spaced from each other aboutsuch axis, a first resilient flexible arm fixed to the shaft forrotation therewith and extending radially therefrom, a second resilientflexible arm fixed to the shaft for rotation therewith and extendingradially therefrom in juxtaposed relation to the first arm and to thecam portions, said first and second arms being spaced from each otheralong the axis of the shaft,

cam follower means on the second arm engageable with the cam portionsfor displacing the arm in opposite directions in the plane of the axisof the shaft responsive to engagement and disengagement of such meanswith the cam portions, a first electrical contact on the first arm, asecond electrical contact on the second arm in juxtaposed relation tothe first electrical contact and normally spaced therefromlongitudinally of the axis of the shaft, the maximum spacing of thefirst and second electrical contacts being less than the maximumdisplacement of the second contact resulting from said displacement ofthe second arm, and means connected to the first and second contacts forconducting electrical current through the contacts when the contacts areengaged, whereby the first and second electrical contacts aresuccessively engaged and disengaged to successively close and open anelectrical circuit.

4. A circuit breaker comprising a rotary shaft, means for rotating theshaft, a non-rotatable member surrounding the shaft and extendingtransversely of the axis of the shaft, a plurality of cam portions onthe member extending therefrom longitudinally of the axis of the shaftand radially spaced equally from the axis of the shaft concentricallywith such axis, said cam portions being of equal angular extent aboutthe axis of the shaft and being spaced from each other symmetricallyabout such axis, a first resilient flexible 'trm fixed to the shaft forrotation therewith and extending radially therefrom, a second resilientflexible arm fixed to the shaft for rotation therewith and extendingradially therefrom intermediate the first arm and the cam portions injuxtaposed relation to the first arm and to the cam portions, said firstand second arms being spaced from each other along the axis of the shaftand being made of electrically conductive material, cam follower meanson the second arm for displacing the arm in opposite directions in theplane of the axis of the shaft responsive to engagement anddisengagement of such means with the cam portions, a first electricalcontact on the first arm in electrically conductive relation thereto, asecond electrical contact on the second arm in electrically conductiverelation thereto in juxtaposed relation to the first electrical contactand normally spaced therefrom longitudinally of the axs of the shaft,said spacing of the first and second electrical contacts being less thanthe maximum displacement of the second contact resulting from saiddisplacement of the second arm, at least one of said first and secondelectrical contacts having an arcuate surface juxtaposed to the adjacentsurface of the other, and means connected to the first and secondcontacts for conducting electrical current through the contacts when thecontacts are engaged are successively engaged and disengaged tosuccessively close and open an electrical circuit.

5. A circuit breaker comprising a rotary shaft, means for rotating theshaft, a member surrounding the shaft and extending transversely of theaxis of the shaft, a plurality of cam portion means on the memberconcentric with the axis of the shaft for displacement of a cam followeraxially of the shaft, 2. first arm fixed to the shaft for rotationtherewith and extending radially therefrom, a second resilient flexiblearm fixed to the shaft for rotation therewith and extending radiallytherefrom, cam follower means secnred to the second arm and engagingsaid cam portion means for displacing the second arm in oppositedirection axially of the shaft responsive to engagement anddisengagement of the cam follower means with the cam portion means, afirst electrical contact on the first arm, a second electrical contacton the second arm in spaced aligned relation axially of the shaft tosaid first electrical contact, a source of electrical potential,electrical means to be switched by the circuit breaker, means forelectrically connecting the source of potential and one of theelectrical contacts, and means for electrically connecting the otherelectrical contact and the electrical means, whereby an electricalcircuit is alternately closed and opened through engagement anddisengagement of the first and second electrical contacts responsive todisplacement of the second arm by the cam portion means.

6. A. circuit breaker for periodically interrupting the flow of electricpower from a source of electric power to an electr'cally powered meanscomprising a rotary shaft, means for rotating the shaft, a stationarymember surrounding the shaft and extending transversely of the axis ofthe shaft, means for varying and selectively releasably the stationaryrotary position of the member about the shaft, a plurality of camportions on the member extending therefrom longitudinally of the axis ofthe shaft and equally radially spaced from the axis of the shaftconccntrically about such axis, said cam portions being spaced from eachother symmetrically about such axis, a rotor disposed on said shaft forrotation therewith, said rotor being made of a dielectric material, a.first resilient flexible arm fixed to the rotor for rotation therewithand extending radially of the shaft, a second resilient flexible armfixed to the rotor for rotation therewith and extending radially of theshaft in juxtaposed relation to the first arm and to the cam portions,said first and second arms being spaced from each other longitudinallyof the axis of the shaft and being made of electrically conductivematerial, cam follower means on the second arm engageable with the camportions for displacing a portion of the second arm axially of the shaftresponsive to engagement of the cam follower means with the camportions, a first electrical contact on the first arm in electricallyconductive relation thereto, a second electrical contact on the secondarm in electrically conductive relation thereto in juxtaposed relationto the first electrical contact and normally spaced therefromlongitudinally of the axis of the shaft, said first and secondelectrical contacts being located radially of the shaft intermediate thecam portions and the shaft, the maximum spacing of the first and secondelectrical contacts from each other being less than the displacement ofthe second contact resulting from said displacement of the second armresponsive to engagement of the follower means with the cam portions,first and second electrical terminals associated with the stationarymember, means for maintaining continuous electrical connection betweenthe first terminal and the first contact, means for maintainingcontinuous electrical connection between the second terminal and thesecond contact, means electrically connecting the power source to one ofthe terminals, and means electrically connecting the electricallypowered means to the other contact, whereby the first and secondelectrical contacts are successively engaged and urged together anddisengaged to successively close and open an electrical circuit betweenthe power source and the electrically powered means.

7. A circuit breaker comprising a rotatable shaft, a plurality of cammeans disposed concentric to the shaft and at equal distances therefrom,each cam means defining a profile having first and second portionsspaced apart from one another axially of the shaft, a pair of resilientparallel arms spaced apart from each other axially of the shaft, meansconnected to the shaft for providing rotational motion between the cammeans and the arms, one arm including a cam follower portion engageablewith the cam means, cooperating electrical contact elements on the arms,the contact elements being disengaged when the cam follower portion isengaged with the first portion of a cam means, the contact elementsbeing engaged when the cam follower portion is engaged with the secondportion of a cam means, and means for maintaining a continuouselectrical connection between each contact element and a correspondingterminal remote from the shaft.

8. In an ignition system for an internal combustion engine comprising anelectrical induction transformer having primary and secondary windings,a source of electric potential, a plurality of spark plugs connectedindividually in a predetermined sequence to the secondary winding,

and a circuit breaker connected for making and breaking an electricalcircuit to the primary winding according to a predetermined rate relatedto the predetermined sequence, the improvement residing in a circuitbreaker comprising a rotatable shaft, stationary cam means disposedradially of the shaft, the cam means defining a profile having a dwellportion and a pause portion parallel to each other and orientedperpendicular to the shaft at longitudinally spaced-apart locationsrelative to the shaft, first and second parallel and spaced-apartresilient arms of electrically conductive material secured to the shaftfor rotation therewith, the arms extending radially of the shaft, thefirst arm extending to a free end adjacent the cam means, cam followermeans at the free end of the first arm engageable with the cam means,cooperating electrical contact elements on the first and second arms,the contact elements being spaced apart axially of the shaft when thecam follower means is engaged with a pause portion of the cam means, thecontact elements being engaged when the cam follower means is engagedwith a dwell portion of the cam means, a pair of terminals forming aportion of a circuit of the ignition system, and means for maintainingcontinuous electrical connection between each of the contact elementsand the terminals.

9. In an ignition system for an internal combustion engine having anelectrical induction transformer having primary and secondary windings,a source of electric potential, a plurality of spark plugs connectedindividually in a predetermined sequence to the secondary winding, and acircuit breaker connected for making and breaking an electrical circuitto the primary winding according to a predetermined rate related to thepredetermined se quence, the improvement residing in a circuit breakercomprising a rotatable shaft, a plurality of cam means disposedconcentric to the shaft and at equal distances therefrom, each cam meansdefining a profile having first and second portions spaced apart fromone another axially of the shaft, a pair of resilient parallel armsspaced apart from each other axially of the shaft, means connected tothe shaft for providing rotational motion between the cam means and thearms, one arm including a cam follower portion engageable with the cammeans, cooperating electrical contact elements on the arms, the contactelements being disengaged when the cam follower portion is engaged withthe first portion of a cam means, the contact elements being engagedwhen the cam follower portion is engaged with the second portion of acam means, and means for maintaining a continuous electrical connectionbetween each contact element and a corresponding terminal remote fromthe shaft.

Shearer Oct. 23, 1923 Hartzell Feb. 13, 1940 UNITED STATES PATENT OFFICECERTIFICATE OF CORRECTION Patent No 3,116 379 December 31 1963 Frank M,Foster It is hereby certified that error appears in the above numberedpatent requiring correction and that the said Letters Patent should readas corrected below.

Column 6, line 26, strike out "and the second electrical contact'hSigned and sealed this 23rd day of June 1964.,

ERNEST W. SWIDER v EDWARD J. BRENNER twisting Officer Commissioner ofPatents M llllll UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPatent No, 3, 116,379 December 31 1963 Frank M, Foster It is herebycertified that error a ent requiring correction and that the sacorrected below. I

ppears in the above numbered patid Letters Patent should read as Column6, line 26, strike out "and the second electrical contact'k Signed andsealed this 23rd day of June 196 1 (SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER tits/sting Officer Commissioner ofPatents

1. A CIRCUIT BREAKER COMPRISING A ROTARY SHAFT, MEANS FOR ROTATING THESHAFT, A MEMBER SURROUNDING THE SHAFT AND EXTENDING TRANSVERSELY OF THEAXIS OF THE SHAFT, A PLURALITY OF CAM PORTION MEANS ON THE MEMBEREQUALLY SPACED FROM THE SHAFT CONCENTRICALLY WITH ITS AXIS AND SPACEDFROM EACH OTHER ABOUT THE SHAFT FOR DISPLACEMENT OF A CAM FOLLOWERAXIALLY OF THE SHAFT, A FIRST ARM FIXED TO THE SHAFT FOR ROTATIONTHEREWITH AND EXTENDING RADIALLY THEREFROM, A SECOND RESILIENT FLEXIBLEARM FIXED TO THE SHAFT FOR ROTATION THEREWITH AND EXTENDING RADIALLYTHEREFROM, SAID FIRST AND SECOND ARMS BEING JUXTAPOSED AND SPACED FROMEACH OTHER AXIALLY OF THE SHAFT, CAM FOLLOWER MEANS DISPOSED ON THESECOND ARM ENGAGEABLE WITH THE CAM PORTION MEANS FOR DISPLACING THESECOND ARM IN OPPOSITE DIRECTIONS AXIALLY OF THE SHAFT RESPONSIVE TOENGAGEMENT AND DISENGAGEMENT OF THE CAM FOLLOWER MEANS WITH THE CAMPORTION MEANS, A FIRST ELECTRICAL CONTACT ON THE FIRST ARM, A SECONDELECTRICAL CONTACT ON THE SECOND ARM IN SPACED ALIGNED RELATION AXIALLYOF THE SHAFT TO